(1) Field of the Invention
The present invention generally relates to electric motor drive vehicles using power supplied from a Diesel electric generator mounted on the vehicle and using electric power from an external source. The present invention specifically relates to a device for locking a pantograph on such a vehicle.
(2) Description of the Prior Art
In the abovementioned Diesel electric motor drive vehicle, a "trolley assist system" may be used depending upon the local requirements. This trolley assist system is used in order to save fuel costs and to improve driving characteristics. It may be used in locations where the vehicle goes up a steep slope. In the trolley assist system, an electric trolley wire is installed over a certain distance on the route and a pantograph mounted on the vehicle in order to collect the electric power for the trolley. The trolley motor is driven by the electric power supply from a base station and the Diesel generator electric source on the vehicle is cut off.
In such trolley assist systems, trouble is experienced in locking the pantograph when it is not in use outside the trolley assist zone. Here the vehicle is running using the vehicle mounted Diesel electric generator power source and the pantograph is folded down in the inoperative condition. The consequences of the inoperative position of the pantograph are dramatic when the vehicle is running on an extremely bad road such as mining transportation road through which the minerals are transported or in a newly developed off-road site. In such areas, the vehicle and folded pantograph are subjected to very strong vibrations or shocks.
When strong vibrations or shocks are applied to the vehicle, they are also transferred to the equipment mounted on the vehicle. This can cause serious trouble for the pantograph, which is usually made of light weight material to allow quick following against the trolley in the trolley assist zone. When the vehicle is running on the uneven ground where no trolley wire is installed and thus the pantograph is kept in the inoperative folded position, the hard shocks or vibrations may cause damage or breakage of the pantograph frame structure or to the pantograph current collector. Prior art locking systems have come unlatched during such shocks. In order to avoid such breakage, it is desirable that the pantograph frame structure and/or collector be locked rigidly and securely.